Glow discharge tube



June 9, 1936. H. EPSTEIN GLOW DISCHARGE TUBE Filed June 22, 1951 Patented June 9, 1936 UNITED. STATES" PATENT OFFICE.

GLOW DISCHARGE TUBE Hirsch Epstein, Chicago, Ill., assignor of twentyflve per cent to Morris L. Epstein and twenty-- five percent to Bernard Epstein, Chicago, Ill.

Application June 22, 1931, Serial No. 545,884

10 Claims.

This invention relates to glow discharge devices of the general type known as neon signs although it is not limited tosuch devices as employ neon gas particularly. The invention is pri-- Consider a neon tube sign of the ordinary type,-

for illustrative purposes. This sign comprises a transparent glass tube bent to the proper configuration and filled with neon gas to a predeterl5 mined pressure so that-when current is made to flow through the tube a luminous glow is pro duced. Since the gas and the tube are both colorless, the sign is not visible, oris only'barely visible,'when no current is flowing through the same, as during the day time. It is an object of the present invention to improve theconspicuity of a sign of this kind at times when it does not carry current, without at the same time detracting from its appearance when it does carry ourrent. 5

It is a further object of the present invention to increase the intensity of illumination produced by signs of this kind. Part of the light that'is produced goes through the front of the tube and is therefore useful for the purposes intended.

'- About half of the light however passes through the back of the tube and is wasted. It is one of the objects of the present invention to provide a tube of this kind with some'arrangement whereby at least a portion of the light which heretofore was wasted through the back of the tube willbe directed through the front of the tube thereby increasing the amount) of light that would otherwise pass through the front of the 40 tube. v

In order to render the tube orsign more conspicuous at daytime I make the back of the tube ofcolored glass, and in order to increase the amount of light that is directed forward when current flows through the tube I make the coloring such as to reflect some of the light which v strikes back of the tube. A tube wherein'a por-- tion at least'iscolored is by far more conspicuous than is a transparent tube and will stand out distinctly at daytime. The whe ls not colored throughout because such coloring; although permitting light to pass through it, would necessarily shut oi! some of the light which is otherwise emitted from the tube when the same has ourrent flowing through it. v

It is a further object of the present invention to provide a sign of the above. character wherein the backing may be of various colors in order to produce pleasing effects when the tube is illuminated. If the backing is of the same color as the 5 colorof the light emitted by the glow' discharge I it will materially increase the intensity of illumination of the device when viewed from the front. It the color of the backing is different from the I color of the light emitted by the glow discharge 10 of'the particular tube thena two color efl'ect is produced which is of striking appearance and readily attracts the attention of an observer. Such tubing is also more readable when the sun strikes it. The backing may be of two or more 15 difierent colors which gives the tube a' multicolor efl'ect.

In connection with neon tube signs it has been observed that the light appears to emanate from a thin pencil or ribbon of light within the tube. 20 When illuminated such tubes appear to be of appreciably smaller diameter than their actual diameter. By my invention the apparent-diameter of a neon tube is increased as compared to the apparent diameter of a similar sized tube 25 heretofore used. This is due'to the colored backknown in the art. The advantage of colored glass 35 over paint is that pmnt must be removed before repumping of the tube since paint carbonizs. I may alsomake the back of the tube of laminated construction and 'interpose the coloring material between the laminae. This latter ar- .40 rangement ofl'ers the possibility of using a. phosphorescent chemical for the coloring matter so that the material -will become phosphorescent when the current is turned ofl. Some phosphorescent materials are activated only by ultra- 4 violet light and where such chemicals are used I prefer to use a tube made of glass which is itself transparent to ultra-violet light so that the 'ultra-violet rays produced by the glow discharge may activate the phosphorescent material. 50 Ultra-violet light is produced if the tube contains mercury vapor. Luminous calcium sulphide represents one suitable phosphorescent substance that is activated-by ultra-violet light. This is merely one of alarge and well known class of 55 tected by a suitable outer layer of paint, lacquer,

may comprise alternate circles or collars of difphosphorescent substances any one of which may be used without departing from the spirit or scope of the present invention. If desirable the phosphorescent substance may be coated on the,

inner back sideof the tube or it may be coated on the outer back sideof the tube and then propaper, orthe like. "When the phosphorescent substance is on the inside of the tube a tube of ordinary glass may be used whereas if it is on the outside'of the tube then the glass of the tube must be transparent to ultra-violet light if the phosphorescent substance used is one ofv the kind that must receive ultra-violet light 'in order to be activated.

' In the ordinary usage of my invention con template arranging the coloring matter in 'strips I extending longitudinally of the glass'tube. The coloring matter would then be entirelyon the back side of the tube and may extend for half of the circumference of theftube'or slightly more or less than half of the circumference of the tube. For certain decorative efi'ects the colored strips may be arranged spirally on the tube .and may compriseone or more spirals of different colored glass. For other striking effects the glass tube 1 of the alphabet being indicated;

Figure 2 representsa cross section ofthe tubing comprising the sign shown in Figure 1;

Figures 3 to 7 inclusive, represent cross sec tions of various different forms of tubing which may be used in a sign such as is shown in Figure 1;

Figure 8 is a fragmentary longitudinal view of a modified form of glass tube wherein the coloring is arranged in a spiral; Figure 9;shows a still different form of tube whereinthe coloring comprises a plurality of spirals; and

Figure lofisalongitudinal view of a modified n form of tube wherein thecoloring comprises collars of difierent color of glass.

. Iteferenee may nowbe had more particularly to-Figure 1." I have there, shown a number of let 'ters of a glow portion indicated at 4. This glow'dischame sign may be one of the kind commonly known as neon signs andcomprises' glass tubing of'substantially uniform thickness bent to the proper config "termined pressure. While neon gas is most commoniy used such signs are not limited to the use of neon gas since there are many other gases ,r. which may be used. as'is well known in the art.

within the tube for producing a luminous Suitable electrical connections [are provided for passing an electric current through the "gases which appears as a pencil of light fextending lengthwise in the tube. This is all well known in the art and no further description thereof is deemed necessary at this time.

My glow discharge differs from dischar e sign. This'is merely I illustrative and comprises three letters of the alphabet indicated at I, 2, and 3, and adecorative tion and filled with a suitable gas and a predeglow signs heretofore known inthe type of glass used In Figure 2 there is shown. cross section of, a representative glass tubing of which the sign shown in Figure 1 is made.

vided with an indentation into which is fitted another piece of glass indicated at Ii; The inner rear side I3 of .thetube may be integral with the front, portion ill. Between the'inner portion The front portion of the tube compri'ses'a colorless piece of glass indicatedat ill, the'rear wall of which is pro- I; and the outer portion ll there is placed some mately united with the portion II at the meeting lines so as to form one continuous tube therewith.

In effect the portions II and i3- comprise two' laminae withfpigment i4 interposed between them. The strip H extends longitudinally of the coloring pigment It. The glass portion II is intitube and, in this form of my invention; is free of anyhelical twist. The tube'shown in Figure 2' may be made by extruding the' material through suitable dies to form a tube with an indentation 011 the outerback side for receiving the portion I I. The pigment may then be applied and thereafter the portion ll united with the rest of the tube by extruding the same through suitable dies.

It may also be made by first forming thelaminae ii and I3 as two separate pieces or strips, interposing the pigment between them, and then uniting those pieces with afront portion such as the portion In, which front portion would of course be initially devoid of a portion such-as the portion I3 shown integral with the portionl0.

. It is,-of course, to. be understoodthat theabove statements as to how, the tube may be made are not the-essence of the present invention, it being understood that the tube may be made by any other desirable or preferred method. n

The pigment material l4 may comprise a phos phorescent substance or a. substance-which becomes phosphorescent when it has been exposed to the action oi light,or of ultra-violet light. If

the substanceused is one thatrequires a'ctiva5 light then the parts used, or

tion by ultra-violet at'least that; portion of glass indicated at l3, should be of thekind transparent to ultra-violet light. Quartz glass is one such suitable glass and there are othersknown in the art. Thefront glass portion tion ll may be either colorless or colored glass.

While I have shown the lines ll l 5 which represent the juncture between the portion II and the portion In it is to be understood that, when these portions are actually Joined the glass flows to- I0 is colorless whereas the rear po'r-' v gether so that suchlines are not visible in the finished product. I g c Inthe tube indicated in section'in Figure 2,

the colorless front portion of the tube extends for somewhat more. than of the periphery. In. the modification shown in Figure 3 this portion extends exactly 180' and'in the modification illustratedin section in Figure 4 this colorless front portion extends v for somewhat less than I 180. Similar, parts 'inFigures 2, 3. and ,4 have been indicated by similar reference numerals, the reference numerals in Figure 3 being primed and .-the reference numerals in'Flgure 4 being given a double prime notation. In other respects modifications shown in Figures 3-and 4 are identi-' 1 caltothatshowninl'igurez.

The coloring material ll hether it be of-a phosphorescent substance or not, renders the same by far morevisible at daytime when itis not illuminated than are corresponding signs whichare made of a single piece of colorless glass.

Inaddition, some of the light whichwould ordinarily pass through the back wall of the tube and be wasted is now reflected forward and serves. to increase the intensity of illumination at the front of the tube. There is another and quite distinct advantage in having the coloring matter I. In

glow discharge devices employing glass tubing colorless throughout, the glow appears to emanate from a narrow pencil or ribbon of light. When viewed at even a slight distance such a tube appears to be of the diameter of the ribbon of light.

tube appears of a larger diameter than the ap-. pearance of a similar tube without the coloring or i apart bycolorless portions 42.

pigment.

In Figure 5, I have illustrated a section of a form of tubing which differs from that of Figure 4 in that two different colored pigments are used. The two different colored portions are indicated at Ma and Nb respectively. The coloring material of Ila may be red and the coloring material of llb blue, although any other colors may be used. These different pigments may both be of phosphorescent material or only one or the other may be phosphorescent, or neither maybe phosphorescent. In other respects this tube is the same as that shown in Figure 4. The showing in Figure 5 is merely illustrative and as such it has been shown in connection with the tube wherein the coloring portion extends for slightly more than half way around the tube, as in Figure 4. It is however to be understood that the arrangement shownin Figure 5 may be arranged so that the coloring matter extends for just 180 of the periphery of the tube, as in Figure 3, or for someportion 20 is'of colorless glass.

as in Figure 2.

In Figure 6, I have shown a cross section of still another form of,tube., This tube comprises two pieces of glass 20 and 2| united to form a seamless tube. While I,have herein shown the meeting edges of these two segments at" and 23 respectively, it is to be understood that when the two glass portions are united they merge or melt into one another and no line of demarcation between them may be seen. The portion 20 repre' .sents the front portion of the sign and the portion 2| the rear part of the sign. The portion 2| is of colored glass, being of any desired color, such as red, yellow, green, blue, or violet. The While I have herein illustrated the colored portion 2| as extending for somewhat less than 180 of the periphery of the tube this may be departed from as in Figure 3 so that the colored portion extends just 180, or for somewhat more than 180 of the periphery of the tube. The colored glass used is preferably transparent, although opaque glass may be used.

The forms of my invention illustrated in Figure 6 may be further departed from by'using two diflerent colored portions 2! and 2| in the manner indicated at Ila and Nb of Figure 5.

In Figure 7 I show a cross section of a tubing wherein the front portion comprises a red glass' section 26, a colorless section 21, and a blue sec.- tion 28. The rear portion maybe colorless and provided with a forward light directing reflector 29. This glow discharge tube may employ helium gas, which emits a white light. The front of the tube therefore appears as red, white, and blue when illuminated. I

tudinally of the tube. not limited to this arrangement since the same In the forms of tubing illustratedin Figures 2 to'7 inclusive, the colored portion extends longi- The invention is however may be arranged in the form of a spiral, as indi cated in Figures 8 and 9 or in any other form. In Figure 8 the colorless portion of the glass is indicated at 30 and the colored portion is indicated at 3| both portions extending in spiral form.

The glass tube indicated in Figure 9 has three spirals, namely the spirals 35 and 36 of different colors such as red and blue and the spiral 31 of colorless glass. Any number of different colors may be thus spiraled around in tubular formation.

In Figure 10 I have shown a tube wherein the various colored portions indicated at 40 and 4| are arranged in collar formation and spaced Various colored effect may be produced in this manner.

When using a backing of a single color the color chosen may be the same as that of the light emitted by the particular tube. For instance, if the gas used for producing the glow is neon, which produces a red light, a red backing may be used. Blue, green, and yellow discharges areproduced by different gases and in those arrangements the backing would be made of a corresponding color. Where a contrast or a different effect is desired the color of the backing may be chosen to be different from the color of the light emittediby "the particular gas used in the glow discharge delimited to those precise, forms, the same being merely illustrative of the broad principles of my invention. What I consider new and desire to secure by Letters Patent is: p

1. A glow discharge sign comprising a glass tube of a plurality of strips of different colored glass twisted in helical formation, and means for passing an electric current through the tube.

2. A glow discharge sign comprising a long and comparatively narrow glass tube of substantially circularcross section bent into shape to constitute the sign and characterized in that the rear side of the glass tube is colored and of a color visible from the front side and the front side is of a plurality of different colors. y

3. A glow discharge sign comprising .a long and comparatively narrow glass tube bent to constitute a letterof the alphabet and containing a conducting gaseous atmosphere and having means for passing an electric current therethrough,. characterized-in that the rear side of' the tube is colored and of a color visible from the front side, said coloring being free of electroso a static action on the device and the front side of the tube being of a plurality of different colors. 4. A glow discharge device comprising a single walled glass tube with coloring matter inter- 70 posed between the inner and outer surfaces of the wall of the tube, and means for passing an electric: current therethrough.

5. A glow discharge device comprising a glass between the inner and outer surfaces thereoiand extending spirally of the tube.

6. A glow discharge sign comprising a substantially circular glass tube defining a single, circular chamber in cross-section,-,said chamber having a filling of gas of the type that pro-' duces a luminous glow of distinctive color upon the passage of an electric current therethrough,

said tube being comparatively long in relation to its diameter and bent into shape so that the 1 luminous glow extends longitudinally of the tube and constitutes the display portion o1 the sign,

characterized by the fact that at least a subcircular chamber in crossisection, said chamber having afilling of gas of the type that pro duces a luminous glow of distinctive color upon the passage of an electric current therethrough, means for passingan electric current there-- through, said tube being comparatively long in relation to its diameter and bent into shape so that the luminous glow extends longitudinally of the tube and constitutes the display portionot' the sign, characterized by the fact that the glass tube has a colored spiral formed thereon and bi a color distinctly diiTerent from the charactergaseous filling, and pervious'to the light of the glow discharge. 1

8. A glow discharge sign comprising a substantially cylindrical glass tube defining a single circular chamber in cross-section, said chamber having a filling oil gas of the type, that produces aluminous glow oi'distinctlve color upon the pas sage of an electric current therethrough, means I for passing anelectric current therethrough, said tube being comparatively long in relation to its diameter and bent into shape so that the luminous glow extends longitudinally of. the tube and constitutes the display portion of the sign, characterized by the fact that a substantial amount of istic' color oi the luminous glow produced bythe is colorless and a substantial amount of the exposed part of the same circular section, 01' the tube is colored glass 01' a color distinctly diflerent from the characteristic color of the glow produces a luminous glow of distinctivecolor upon duced by an electric discharge through the filling. v

9. A glow discharge sign comprising a cy-V lindrlcal singlewall glass tube defining a single circular chamberin oross-section,v said chamber having a filling oi gas oi the type that prothe. passage of an electric current 'therethrough,' means for passing an electric current through the. tube, said tube being comparatively long in relation to its diameter and bent into shape'so 1 that the luminous glow extends longitudinally of the tube and constitutes the display Portion of 1 the sign, characterized by the fact that, in a i. transverse cross-section, a substantial amount of the exposedpart of the tube is colorless glass and 20 a substantial amount of the exposed part oi the tube is colored glass, boththe colorless and the colored portion of the tube being 0! transparent glass. I i

the exposed part of a circular section of the tube 10. A glow discharge sign comprising a glass tube of glass of substantially uniform thickness bent into shape to constitute the displayportion oi the sign, said tube containing a gas of the type that produces a luminous glow of a distinctive color upon the passageroi' an electric current therethrough, means for passing an electriccur rent through the gas within the tube for prm ducing ,a luminous glowithe tube being comparatively long in relation to its diameter so that the glow constitutes a pencil of light oi the shape3 oi the display portion of the sign thei'ront of v the tube being clear colorless transparent glass and the rear of the tube behind the colorless front portion being coloredoi' thesame distinctive color as that of the luminous glow, to reflect forward 40 I some of thelight oi the luminous glow,and also to reflect forward at least a substantial portion or extraneous light that may strike it when no electric current is passing through the tube, and

the colored portion or the tube being also pervious to the light of the glow, discharge whereby at least a fractional part or the light of the glow discharge passes through the back oi'the tube.

a HIRSCH EPSTEIN; 

